Antennas for personal communication devices, such as radiotelephones, may not function adequately when in close proximity to a user during operation, or when a user is moving during operation of a device. Close proximity to objects or movement of a user during operation of a radiotelephone may result in degraded signal quality or fluctuations in signal strength, known as multipath fading. Diversity antennas have been designed to work in conjunction with a radiotelephone's primary antenna to improve signal reception.
Many of the popular hand-held radiotelephones are undergoing miniaturization. Indeed, many of the contemporary models are only 11-12 centimeters in length. Unfortunately, as radiotelephones decrease in size, the amount of internal space therewithin may be reduced correspondingly. A reduced amount of internal space may make it difficult for existing types of diversity antennas to achieve the bandwidth and gain requirements necessary for radiotelephone operation because their size may be correspondingly reduced.
Furthermore, it may be desirable for a diversity antenna to be able to resonate over multiple frequency bands. For example, the Japanese Personal Digital Cellular (PDC) system utilizes two "receive" frequency bands and two "transmit" frequency bands. Accordingly, a diversity antenna within a radiotelephone used in the Japanese PDC system should preferably be able to resonate in each of the two receive frequency bands. Unfortunately, the ability to provide diversity antennas with adequate gain over multiple frequency bands may be presently limited because of size limitations imposed by radiotelephone miniaturization.